Portals such as ArcGIS Online and ArcGIS Enterprise can store many types of data.
Perhaps the type most commonly used by apps is a web map—a JSON description of the data in a map, along with other display and behavioral
properties. Other types include tile packages, feature collections,
and services. Some types, such as globe documents and map
templates, may only be relevant to desktop systems. Although you
can access these types of data using the API, you may not be able to use
them on a mobile device. Some types of data can be taken offline.

PortalItem represents an individual item stored on a portal. Each item
includes the following:

Binary or text-based data—for example, the JSON that defines a web map or a feature collection, or a URL pointing to a map service, or the binary data of a tile package or shapefile

Apps use portal items in different ways. They may show a user a
range of items from a portal by combining the title, thumbnail
image, and other metadata. This approach is often used to allow users to browse web maps,
basemaps, or map services, and identify the item to work with. If a
user selects an item, the app may then download the data stored in
the portal item, for example, by opening and displaying a web map in
a map, or downloading a tile package. Apps sometimes access items
directly by ID if a specific item should always be used.

Your
app can also add new portal items and alter existing items by
adding comments and ratings, updating item information, sharing,
unsharing, and deleting them, as long as the authenticated user has
access permissions to do so.

You access the content of a portal item differently depending on
its type. Below you can find examples of accessing different types
of portal items. For more information on connecting to a portal, see
Access the ArcGIS platform.

Display a web map by ID

A very common task is to display a web map from a portal. Web maps are stored as portal items and can be opened by using the ID of the item, along with the URL of the portal. If the map is not public (for example, if it is shared only with a specific group), you also need to pass in valid credentials with permission to view the map. See Access the ArcGIS platform for more information on accessing secured items.

In the following example, the web map portal item is opened using the PortalItem.CreateAsync static method. The item is passed to the constructor for a new Map, which is then displayed in the map view.

Open a map

You can create a map from a web map portal item without needing to display it immediately. From this, you could find out more about the contents of the map before displaying it if required—for example, getting the basemap, operational layers, bookmarks, and initial extent. To do this, load the map before setting it into a map view—see Loadable pattern for more information.

The following example gets a web map portal item, finds one of its bookmarks, and then zooms to the extent of the bookmark.

Note:

Remember that you must also specify credentials for a valid user with access to the item, if the item is not publicly shared.

Create a layer from a service item by ID

Portal items representing map or feature services can be used to
create layers by using the portal item URL. The following example gets a portal item that represents a feature service and reads the URL. The first layer in the service is added to the map.

// connect to ArcGIS Online
ArcGISPortal arcGISOnline = await ArcGISPortal.CreateAsync();
// create an PortalItem using a portal item ID
var portalItem = await PortalItem.CreateAsync(arcGISOnline, "9fb4d96077e24bcba72ba6cf1139c9cf");
// check the item type to make sure its a feature service
if(portalItem.Type != PortalItemType.FeatureService) { return; }
// build a URL to the first layer in the service
var uri = new Uri(portalItem.Url + "/0");
// create a new service feature table referencing the service
var table = new ServiceFeatureTable(uri);
// create a new feature layer from the table
var layer = new FeatureLayer(table);
// add the layer to the map
MyMapView.Map.OperationalLayers.Add(layer);

Find information about any portal item by ID

You can use the ID of any item stored in a portal to access it, and also to find its fields—properties such as its title, description, thumbnail image, owner, and any ratings or comments added by portal users. You can also find out the type of data it contains.

Note:

The thumbnail of a portal item, along with the ratings and data, is not returned from the portal when you initially load the item, in order to reduce the network traffic and memory requirements. See the section below on how to access these properties.

Fetch thumbnails of items

When you create a portal item object, not all information associated with it is immediately returned. This allows you to work with the item using a minimum amount of memory and delay fetching the larger pieces of data unless, or until, you really need them. Information you need to fetch, if required, includes thumbnail images, ratings and comments, item data, group memberships, and user folder contents.

The following example shows how to create a bitmap image to display a portal item thumbnail.

// get the URL to the portal item thumbnail image
var thumbUri = portalItem.ThumbnailUri;
// create a new bitmap using the URL
var thumbImage = new BitmapImage(thumbUri);
// display the image in a control in the app
ItemThumbnailImage.Source = thumbImage;

The same applies to the thumbnails of other classes, like users, groups, and organizations. Use ThumbnailUri on PortalItem, PortalGroup, and PortalUser. Additionally, PortalInfo provides ThumbnailUri (for the organization) and PortalThumbnailUri.

Access item data

Portal items that represent files, such as tile packages, images, documents, PDF files, and so on, can be opened, downloaded, and then stored or opened in your app or in another app. As in the previous example, you will need to specifically fetch the data of a portal item after you create it. Use the GetDataAsync method to do this.

Fetch a user's content

Many apps present a list of maps or other items that belong to the current user. Users can create folders within their portal accounts to help organize their work. Apps should respect the user's view of their content and present the list of folders to the user, allowing the user to choose which folder to look at in detail.

It's easy to get all the portal items owned by the authenticated user (that represent the content and services items created by that user). PortalUser represents information about a user, and from this you can retrieve all of the items and folders (represented by PortalFolder) owned by the user.

The following example gets folders and items belonging to an authenticated user of a portal.

To get items shared with the current user, or items owned by a different user, you need to search for content.

List the groups a user belongs to

Groups can be configured in different ways—some groups are open to all users; some are only accessible by invitation; and for others, any user can request to join. The groups to which the authenticated user belongs can be accessed, and for any group, the identities of the members can be found.

The PortalGroup class represents a group. You can get a list of the groups a user belongs to by calling the PortalUser.Groups property. Use GetGroupUsersAsync to retrieve the users in each group—after that, you can get the members from the Users property.